Curtius rearrangement
Abstract
The Curtius rearrangement is a thermal [1,2]-migration that converts an acyl azide into an isocyanate with loss of dinitrogen. The isocyanate intermediate can then be trapped by various nucleophiles such as water, alcohols, thiols or amines, giving amines, carbamates, thiocarbamates or ureas respectively.
Keywords
Acyl azide, Rearrangement, Isocyanate, Amine, Carbamate, Thiocarbamate, Urea
Category
Rearrangement, Azide/Acyl azide
Mechanism
Upon heating, the acyl azide undergoes a concerted [1,2]-migration: the R1 group migrates from the carbonyl carbon to the α-nitrogen of the azide, simultaneously with heterolytic cleavage of the Nα–Nβ bond and expulsion of N2, yielding the isocyanate directly.
Recent review
Zavarise, C.; Cintrat, J-C.; Romero, E.; Sallustrau, A. Isocyanate-based multicomponent reactions. RSC Adv. 2024, 14, 39253-39267.